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Adults who received approximately four hours of sleep the previous night were exposed to odors like potato chips or cinnamon rolls, as well as nonfood scents like fir trees. Weeks later, the same participants were asked to sniff the same scents after receiving a full eight hours of sleep.

When exposed to the aroma of foods, subjects who were sleep deprived showed more brain activity in their piriform cortexes and orbitofrontal cortexes - two regions of the brain associated with smell.

That increase in brain activity wasn't seen when people were exposed to nonfood odors.

"We find that across both sleep conditions, fMRI (functional magnetic resonance imaging) responses to food compared to non-food odors were enhanced in posterior orbitofrontal cortex, piriform cortex, and anterior insula," the study said. "By showing that early olfactory responses to food odors are elevated in a sleep-deprived state, our results highlight a role for bottom up modulation in sleep-dependent appetite and eating behavior."